WEDNESDAY, Oct. 29, 2014 (HealthDay News) -- Exposure to a common plastics' chemical during pregnancy may have effects on genital development in baby boys, a small study hints.

Researchers found that baby boys born to moms with greater exposure to a chemical called DiNP tended to have a shorter anogenital distance -- the space between the genitals and anus. Anogenital distance is set in the womb, and it's considered a marker of exposure to androgens ("male" hormones) during pregnancy.

The researchers said their findings, published online Oct. 29 in Environmental Health Perspectives, add to concerns about the possible effects of certain plasticizers on the male reproductive system.

But the authors also acknowledged that the study points to a correlation between DiNP and boys' anogenital distance -- and not necessarily a cause-and-effect relationship.

"We need more studies," said Shanna Swan, a professor of preventive medicine at the Mount Sinai School of Medicine in New York City. "This is one study of a small number of boys."

Still, she said the findings are in line with some research on certain other chemicals in the same group -- known collectively as phthalates.

Phthalates are added to plastics to make them more flexible and difficult to break. They are used in a huge range of products, from electrical cables, auto parts and construction materials to cosmetics, shoes and toys (though U.S. manufacturers stopped using them in pacifiers, teething rings and rattles in 1999). People can also be exposed to low levels of phthalates in food, since much of the food supply comes in contact with plastics.

It's not clear whether phthalates affect human health, according to the U.S. Centers for Disease Control and Prevention.

But animal research has suggested that some phthalates can disrupt normal hormone activity. And a recent study of over 2,000 Americans linked higher phthalate exposure to lower testosterone levels in boys and middle-aged adults.

Swan said questions about DiNP's potential effects are particularly important because the chemical is being increasingly used. In fact, she noted, DiNP has become a "substitute" for an older phthalate -- known as DEHP -- due to concerns about that chemical's safety.

But the American Chemistry Council (ACC), an industry trade group, denied that DiNP has effects on people's hormonal activity.

"As the researchers themselves indicate [in the report], the Chronic Hazard Advisory Panel to the U.S. Consumer Product Safety Commission has concluded that DiNP is a weak anti-androgen in experimental animals," the ACC said in a written response to the findings.

"It produces effects in rats at dose levels that are over 100,000 times higher than typical human exposures," the group added.

For the study, Swan's team measured the anogenital distance in almost 200 Swedish boys, who were 21 months old, on average. They also analyzed urine samples taken from the boys' mothers during the first trimester of pregnancy -- looking for the metabolic byproducts of 10 different phthalates.

In general, the researchers found, the higher moms' phthalate levels were, the shorter their babies' anogenital distance. The link was strongest when it came to DiNP levels.

But why would anogenital distance matter? Swan said shorter distance has been linked to lower fertility in adult men -- though the reasons for the connection are unclear.

And, she noted, "the $64,000 question" is whether baby boys with a shorter anogenital distance maintain that characteristic throughout life.

The other big question is whether phthalates are the true reason for the current findings. "Could it be other chemicals in the environment, or factors other than manmade chemicals?" Swan said.

That cannot be ruled out, she acknowledged. But she also said the findings call into question the process by which one phthalate is phased out due to safety questions, then replaced with another.

"It seems there has to be a better way to do this," Swan said.

The ACC, however, disputed the idea that any type of phthalate, at the public's typical exposure levels, has ill health effects.

"Phthalates have been thoroughly studied and reviewed by a number of government scientific agencies and regulatory bodies worldwide, and these agencies have concluded that phthalates used in commercial products do not pose a risk to human health at typical exposure levels," the group said.

For people who want to limit their phthalate exposure, Swan suggested eating fewer processed foods and more "whole" foods. She said they can also avoid storing and microwaving foods in recyclable plastic containers; containers with the recycling codes 3, 6 or 7 can contain phthalates or another chemical called BPA.